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procfs: get rid of ancient BS in pid_revalidate() uses
First of all, calling pid_revalidate() in the end of <pid>/* lookups is *not* about closing any kind of races; that used to be true once upon a time, but these days those comments are actively misleading. Especially since pid_revalidate() doesn't even do d_drop() on failure anymore. It doesn't matter, anyway, since once pid_revalidate() starts returning false, ->d_delete() of those dentries starts saying "don't keep"; they won't get stuck in dcache any longer than they are pinned. These calls cannot be just removed, though - the side effect of pid_revalidate() (updating i_uid/i_gid/etc.) is what we are calling it for here. Let's separate the "update ownership" into a new helper (pid_update_inode()) and use it, both in lookups and in pid_revalidate() itself. The comments in pid_revalidate() are also out of date - they refer to the time when pid_revalidate() used to call d_drop() directly... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
parent
11f17c9bd7
commit
1bbc55131e
3 changed files with 28 additions and 38 deletions
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@ -1803,15 +1803,22 @@ int pid_getattr(const struct path *path, struct kstat *stat,
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/* dentry stuff */
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/*
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* Exceptional case: normally we are not allowed to unhash a busy
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* directory. In this case, however, we can do it - no aliasing problems
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* due to the way we treat inodes.
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*
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* Set <pid>/... inode ownership (can change due to setuid(), etc.)
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*/
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void pid_update_inode(struct task_struct *task, struct inode *inode)
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{
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task_dump_owner(task, inode->i_mode, &inode->i_uid, &inode->i_gid);
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inode->i_mode &= ~(S_ISUID | S_ISGID);
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security_task_to_inode(task, inode);
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}
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/*
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* Rewrite the inode's ownerships here because the owning task may have
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* performed a setuid(), etc.
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*
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*/
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int pid_revalidate(struct dentry *dentry, unsigned int flags)
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static int pid_revalidate(struct dentry *dentry, unsigned int flags)
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{
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struct inode *inode;
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struct task_struct *task;
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@ -1823,10 +1830,7 @@ int pid_revalidate(struct dentry *dentry, unsigned int flags)
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task = get_proc_task(inode);
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if (task) {
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task_dump_owner(task, inode->i_mode, &inode->i_uid, &inode->i_gid);
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inode->i_mode &= ~(S_ISUID | S_ISGID);
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security_task_to_inode(task, inode);
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pid_update_inode(task, inode);
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put_task_struct(task);
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return 1;
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}
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@ -2438,7 +2442,7 @@ static int proc_pident_instantiate(struct inode *dir,
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inode = proc_pid_make_inode(dir->i_sb, task, p->mode);
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if (!inode)
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goto out;
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return -ENOENT;
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ei = PROC_I(inode);
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if (S_ISDIR(inode->i_mode))
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@ -2448,13 +2452,10 @@ static int proc_pident_instantiate(struct inode *dir,
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if (p->fop)
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inode->i_fop = p->fop;
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ei->op = p->op;
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pid_update_inode(task, inode);
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d_set_d_op(dentry, &pid_dentry_operations);
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d_add(dentry, inode);
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/* Close the race of the process dying before we return the dentry */
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if (pid_revalidate(dentry, 0))
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return 0;
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out:
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return -ENOENT;
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return 0;
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}
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static struct dentry *proc_pident_lookup(struct inode *dir,
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@ -3140,22 +3141,18 @@ static int proc_pid_instantiate(struct inode *dir,
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inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);
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if (!inode)
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goto out;
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return -ENOENT;
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inode->i_op = &proc_tgid_base_inode_operations;
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inode->i_fop = &proc_tgid_base_operations;
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inode->i_flags|=S_IMMUTABLE;
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set_nlink(inode, nlink_tgid);
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pid_update_inode(task, inode);
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d_set_d_op(dentry, &pid_dentry_operations);
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d_add(dentry, inode);
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/* Close the race of the process dying before we return the dentry */
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if (pid_revalidate(dentry, 0))
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return 0;
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out:
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return -ENOENT;
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return 0;
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}
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struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
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@ -3434,23 +3431,19 @@ static int proc_task_instantiate(struct inode *dir,
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{
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struct inode *inode;
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inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);
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if (!inode)
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goto out;
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return -ENOENT;
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inode->i_op = &proc_tid_base_inode_operations;
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inode->i_fop = &proc_tid_base_operations;
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inode->i_flags|=S_IMMUTABLE;
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inode->i_flags |= S_IMMUTABLE;
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set_nlink(inode, nlink_tid);
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pid_update_inode(task, inode);
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d_set_d_op(dentry, &pid_dentry_operations);
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d_add(dentry, inode);
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/* Close the race of the process dying before we return the dentry */
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if (pid_revalidate(dentry, 0))
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return 0;
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out:
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return -ENOENT;
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return 0;
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}
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static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
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@ -147,7 +147,7 @@ extern const struct dentry_operations pid_dentry_operations;
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extern int pid_getattr(const struct path *, struct kstat *, u32, unsigned int);
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extern int proc_setattr(struct dentry *, struct iattr *);
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extern struct inode *proc_pid_make_inode(struct super_block *, struct task_struct *, umode_t);
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extern int pid_revalidate(struct dentry *, unsigned int);
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extern void pid_update_inode(struct task_struct *, struct inode *);
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extern int pid_delete_dentry(const struct dentry *);
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extern int proc_pid_readdir(struct file *, struct dir_context *);
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extern struct dentry *proc_pid_lookup(struct inode *, struct dentry *, unsigned int);
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@ -96,19 +96,16 @@ static int proc_ns_instantiate(struct inode *dir,
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inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK | S_IRWXUGO);
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if (!inode)
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goto out;
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return -ENOENT;
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ei = PROC_I(inode);
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inode->i_op = &proc_ns_link_inode_operations;
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ei->ns_ops = ns_ops;
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pid_update_inode(task, inode);
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d_set_d_op(dentry, &pid_dentry_operations);
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d_add(dentry, inode);
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/* Close the race of the process dying before we return the dentry */
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if (pid_revalidate(dentry, 0))
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return 0;
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out:
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return -ENOENT;
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return 0;
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}
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static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
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